#include <54func.h>
int main(int argc, char *argv[])
{
    // ./0_server_udp 192.168.72.128 1234 
    int sockfd = socket(AF_INET,SOCK_DGRAM,0);
    struct sockaddr_in serverAddr;
    serverAddr.sin_family = AF_INET;
    serverAddr.sin_port = htons(atoi(argv[2]));
    serverAddr.sin_addr.s_addr = inet_addr(argv[1]);
    int ret = bind(sockfd,(struct sockaddr* )&serverAddr,sizeof(serverAddr));
    // 第一次必须是客户端向服务端发消息
    struct sockaddr_in clientAddr;
    socklen_t socklen = sizeof(clientAddr);
    char buf[4096] = {0};
    recvfrom(sockfd,buf,4096,0,
             (struct sockaddr *)&clientAddr,&socklen); // socklen的设置和accept一样
    printf("buf = %s, ip = %s, port = %d\n", 
           buf, inet_ntoa(clientAddr.sin_addr), ntohs(clientAddr.sin_port));
    sendto(sockfd,"world",5,0,
           (struct sockaddr *)&clientAddr, sizeof(clientAddr));
    sendto(sockfd,"world",5,0,
           (struct sockaddr *)&clientAddr, sizeof(clientAddr));
    return 0;
}

